Intuitive concepts in internal medicine and their occurrence in undergraduate medical students in different semesters

Background: Dealing with errors in medical practice is of great importance for patient safety. In the natural sciences, intuitive concepts, so-called misconceptions, are increasingly coming into focus of teaching because they lead to a faulty understanding of contexts and thus to faulty scientific reasoning. In medicine, intuitive concepts still play a subordinate role. However, once intuitive concepts have been memorized, they can become firmly established and, under certain circumstances, lead to diagnostic and treatment errors in medical practice. The aim of this study was to identify potential intuitive concepts in internal medicine and to analyze their occurrence in medical students from different semesters. Methods: Eight internists from different subspecialties were asked about intuitive concepts by means of a structured interview. A total of 17 intuitive concepts were identified. Using these concepts, a multiple-choice test was created with 17 patient cases. For each case, there were four possible answers: the correct answer, an incorrect answer that included the intuitive concept, the answer “both are incorrect”, and the answer “I am not sure”, which is to be understood in the sense of “I do not know whether one of the three answers is correct”. As an online multiple-choice test, these 17 cases were made available to all 2nd, 6th, and 12th semester students (N=1170, n=418 from the 2nd semester, n=425 from the 6th semester, and n=327 from the 12th semester, i.e., the final year) for four weeks in June 2015. The test had to be answered within nine minutes. A mixed logistic regression model was used for evaluation. Results: Of the N=317 participating students (n=97 from the 2nd semester, n=124 from the 6th semester, and n=96 from the internship year, overall response rate 27.1%), on average, students from all three groups chose the intuitive concept most often, approximately 40%, although the correct answer increased toward the final year with simultaneously decreasing uncertainty and decreasing feeling of not knowing, respectively. In the final year, compared to the 2nd semester, the intuitive concept was selected significantly more often for two questions (p<0.01). For four questions, the intuitive concept was selected significantly less frequently in the final year (p<0.01). Conclusion: Intuitive concepts can be identified in internal medicine and do not appear to be significantly reduced in students during the course of their studies. This suggests that this could also be the case for other medical subjects. Therefore, similar studies should be conducted for other medical subjects in order to identify potential sources of error in clinical work. In addition, suitable didactic methods should be developed and tested with which students learn not to succumb to intuitive concepts as far as possible in order to prevent diagnostic or therapeutic errors in later medical practice.


Introduction
Errors happen more often than expected in the daily clinical routine of physicians and can lead to serious patient danger and death [1]. Dealing with errors openly and developing strategies to avoid them are therefore particularly important in medicine, whereby medicine is often accused of having a rather negative culture of dealing with errors [2], while a positive error culture can serve as a resource for avoiding errors [3]. In the context of quality management in hospitals, there has been a particular focus on the avoidance of technical errors, e.g. the administration of an incorrect intravenous drip, which can be well avoided by the introduction of checklists and leads to higher patient safety [4]. However, not all errors fall into this category, which is why it seems important to be confronted with specific types of errors already during undergraduate education in order to build up an explicit knowledge of errors [5]. Which didactic methods are particularly suitable for this purpose has so far only been researched on an exemplary basis [6]. Especially in the natural sciences but also in the humanities, students increasingly describe mental concepts that contradict the content of common scientific concepts [7], [8], [9]. These scientifically untenable notions are referred to as misconceptions or intuitive concepts [10], [11]. They usually stem from simple everyday notions that are often difficult to change despite having been taught in a scientifically correct and the intuitive concept directly contradicting way, because they are deeply embedded in subjective frameworks and have been proven correct in other contexts [12]. Therefore, the term "preconcept" is sometimes used to describe concepts acquired early in non-subject related contexts [13]. A typical intuitive concept from physics, for example, describes the idea of students that force is a cause of motion and that it can be concluded from the presence of motion that a force must be involved. However, this is in direct contradiction to the central statement of Newtonian mechanics and represents an intuitive concept that is retained by students even after successfully passing exams [14]. Therefore, the systematic exploration of intuitive concepts has already led to didactic adaptation of university teaching in some fields [15], [16]. In medicine, too, there are thought processes in the context of clinical reasoning that are based on erroneous concepts and cause so-called cognitive errors, which in turn can lead to incorrect decisions and thus also to treatment errors [17], [18]. Recurring patterns and sequences of decision making required in the diagnostic process may also be the basis for the emergence of intuitive concepts [19]. In particular, medical students and young residents seem to succumb more easily to heuristic misconceptions [20]. Thus, overlaps with intuitive concepts occur here, since misconceptions can have a decisive influence on the scientific decision-making process. For undergraduate medical studies, the presence of intuitive concepts has already been investigated in the subjects of physiology and biochemistry [21], [22]. Further-more, it has been shown that intuitive concepts were frequently selected by students in a multiple-choice examination despite scientifically based teaching in physiology and biochemistry [23]. Previous teaching methods seem to have limited ability to overcome preexisting intuitive concepts [24]. In physicians, for example, the presence of intuitive concepts about the causes of fever or the treatment of chronic constipation has been observed [25], [26]. Therefore, the aim of our project was to identify potential intuitive concepts from the field of internal medicine that may also lead to treatment errors under certain circumstances and to investigate their possible occurrence in medical students with different study progress. Our hypothesis was that the choice of intuitive concepts would not decrease with study progress, because the correctly learned content would be further in the past as the education progressed, and intuitive but incorrect answers might therefore predominate for certain questions.

Project description Qualitative identification of potential intuitive concepts in internal medicine
To identify potential intuitive concepts in internal medicine, at first an interview guide was created for discussions with internists. It included the definition of an intuitive concept as well as examples of intuitive concepts from the scientific fields of mathematics [27] and astronomy [28] and from the medical fields of physiology [23] and nephrology [29]. The subsequent questions aimed to generate possible intuitive concepts or theses from the experiences of the physicians interviewed. In addition to the thesis of a potential intuitive concept, the correct scientific explanation of the medical facts was also enquired. A total of seven clinically active male physicians and one female physician from various sub-specialties of internal medicine (diabetology, endocrinology, gastroenterology, infectiology, cardiology, nephrology, pneumology) from the University Medical Center Hamburg-Eppendorf and medical surgeries in Hamburg participated. The interviews were tape-recorded and transcribed verbatim. A total of 17 intuitive concepts could be compiled from the material (see table 1).

Development of a case-based multiple-choice test to examine the presence of intuitive concepts in internal medicine
To verify the presence of intuitive concepts in medical students, a case-based multiple-choice test was developed from the 17 intuitive concepts identified. Each question was preceded by a brief case presentation reflecting a typical clinical situation, and there were four response options for each case presentation. These included the correct answer, the incorrect answer that matched the intuitive concept, the answer option "both answers are incorrect", and the answer choice "I am not sure" in the sense of "I don't know". Hence, pressure was to be reduced to have to select one of the answer choices within the guessing probability in case of not knowing the answer. Figure 1 exemplary shows the question of the test on intuitive concept no. 11 (heart attack). The complete test with all questions can be found in attachment 1. The test was created digitally on an online platform [https://www.umfrageonline.com] and was conducted in multiple-choice style with single choice and no direct provision of the correct answers. Multiple participations were technically prevented by blocking the session browser ID and setting cookies. When clicking on the first page, after a short explanation of the test structure as a novel case-based multiple choice test with four answer options, the socio-demographic data gender, age and current semester of undergraduate medical study were requested. To ensure that the questions could be answered quickly, the test was time-limited to a maximum of nine minutes, of which the participants were informed. The order of the questions was randomized during test creation. Each question was presented on a single page and only after selecting an answer option was it possible to move to the next question. It was not possible to jump back to previous questions.

Participants
In June 2015, a total of 1170 undergraduate medical students at the University of Hamburg were invited by email to participate, 418 from the second and 425 from the sixth semester as well as 327 from the final year (PJ). It was possible to participate in two periods of two weeks each. Participation in the multiple-choice test was anonymous and voluntary, and students gave consent to the use of their anonymized data by completing the questionnaire. The study was conducted in accordance with the Declaration of Helsinki and a member of the Ethics Committee

Statistical analysis
Statistical analysis of the multiple-choice test was performed using IBM ® SPSS ® Statistics for Windows, version 23. The probabilities of each student group to choose an answer option were calculated, as well as the corresponding means and standard deviations. A mixed logistic regression model was used for further analysis. Outcome parameters were, on the one hand, the probability of succumbing to the intuitive concept and, on the other hand, the probability of choosing the response option "I am not sure" as a measure of uncertainty in the sense of not knowing. The variables used as predictors were the level of education (current semester) and the individual questions of the test. The interaction was tested using likelihood ratio. Gender and age were considered as confounders. Due to the multiple measurements per participant, these had to be modeled as clusters in the logistic regression. The adjusted probabilities of the individual answer options of the multiple-choice test for the subgroups and their pairwise comparison with the corresponding 95% confidence intervals are reported.

Results
A total of 317 of 1170 invited students participated in the online multiple choice test (response rate 27.1%), of which 97 were from semester 2, 124 from semester 6, and 96 from the final year (see table 2). The mean age of all participants was 24.5±4.2 year and 61.2% of participants were female. The proportion of correct answers was greater for final-year students (39.1%) compared with 2 nd semester (22.6%) and 6 th semester (32.1%) students, and uncertainty or feeling of not knowing the answer was lowest (final year: 5.7%, 2 nd semester: 32.0%, 6 th semester: 16.8%). However, the selection of the intuitive concept was approximately 40% overall and represented in all three groups the largest percentage of all responses. Attachment 2 shows the percentages of responses related to each question of the multiple-choice test. The numbers of answers per individual question can be found in attachment 3. Differences emerged for the individual subgroups "2 nd semester", "6 th semester", and "final year" in terms of the calculated probabilities of succumbing to the intuitive concept (see figure 2). For 9 of the 17 intuitive concepts examined, there was an increase in the probability of selecting the intuitive concept among final-year students compared with 2 nd semester students. For the choice of intuitive concepts 1 ("mortality") and 2 ("retinopathy"), the probability was even significantly (p=0.01) increased for final-year students compared to both 2 nd semester and 6 th semester students. Also significantly (p=0.01) greater for these two questions was the probability of succumbing to the intuitive concept for 6 th semester students compared to 2 nd semester students. For intuitive concepts 6 ("antibiotic"), 11 ("heart attack"), 12 ("pacemaker"), and 17 ("smoking"), the probability of choosing the intuitive concept was significantly (p=0.01) lower in final-year studentss compared to 2 nd semester students. There was no correlation with age and gender. Uncertainty in selecting an answer or the feeling of not knowing the answer, respectively (see figure 3), was shown to be significantly (p=0.01) less in final-year students compared to 2 nd semester students for intuitive concepts 1 ("mortality"), 2 ("retinopathy"), 4 ("fluid intake"), 5 ("PTT"), 9 ("febrile seizure"), 14 ("diuretic"), and 15 ("GFR"), although at the same time the probability of succumbing to the intuitive concept increased (see figure 2). Intuitive concepts 1 ("mortality"), 2 ("retinopathy"), and 14 ("diuretic") were also significantly less uncertain for 6 th semester students compared with 2 nd semester students.

Discussion
By interviewing internal medicine residents, we identified 17 intuitive concepts from the field of internal medicine. Although in our multiple-choice test, which included questions on these concepts, the selection of the correct answer increased with increasing semester among the medical students and the uncertainty in answering the questions or the feeling of not knowing the answer decreased, the intuitive concept was chosen as the most frequent answer by students of all semesters. In a study on causes of worsening acne vulgaris, it was also shown that intuitive concepts common in the general population were still highly prevalent among medical students in their final year of study [30]. The consistent percentage per semester of intuitive concept selection for internal medicine topics in our study confirmed studies in medical physiology that existing intuitive concepts appeared to have little to no ability to be overcome by previous teaching methods [24], [31]. Another study of biomedical science students, using a multilayered approach to study intuitive concepts in cardiovascular physiology, could demonstrate that in nearly one-third of the cases the selection of the intuitive concept was paired with high confidence of having answered the question correctly [32]. Unlike in our multiple-choice test, here the degree of uncertainty about the selected answer of the concept should be indicated, whereas in our test not knowing was a separate answer option. Since intuitive concepts on medical aspects impair clinical reasoning and this ignorance may possibly lead to cognitive thinking errors in medicine [33], [34] and thus also to treatment errors, it seems necessary, on the one hand, to identify possible intuitive concepts in the different medical disciplines, as in our study for internal medicine. On the other hand, didactic methods need to be tested that help students to permanently overcome intuitive concepts in medicine. So far, it has been shown that teaching on conceptual change was more helpful for this purpose [35] than supplementary facts or feedback [36], [37]. For some of the intuitive concepts we identified, e.g., "heart attack" and "antibiotic", this may perhaps have been the reason for a reduction in intuitive concept use among students in higher semesters. However, it was also shown that knowledge in evidence-based medicine, which was supposed to counteract medical performance according to intuitive concepts with scientific justifications, deteriorated in students during the final year, whereas this was not the case for knowledge on clinical cases requiring urgent treatment [38]. This suggests that in addition to conceptual changes in scientific thinking, working with mnemonic bridges might also be useful, as has been successfully shown for the use of antibiotics in veterinary medicine [39] or for generating a larger number of differential diagnoses in medicine [40]. However, this assumes that possible intuitive concepts are known. If this is the case, such techniques could be complementarily helpful to avoid having to remember the correct scientific background during fast clinical decisions, as simulated by the time limit in our multiple-choice test, and then mistakenly succumbing to the intuitive concept after all. In our study, we were able to show for the first time that intuitive concepts exist in the various fields of internal medicine. However, a weakness of the project is that not all areas of internal medicine were investigated and that it was not a systematic survey, so that the number of intuitive concepts identified could be incomplete. In addition, in the design of the multiple-choice test, the item "I don't know" should have been chosen instead the item "I am not sure", since the question was about knowledge of a concept and not about the feeling of uncertainty in, for example, medical-diagnostic decisions [41]. Furthermore, it was not taken into account that despite the four possible answers there may have been a certain guessing probability, since the distractor "both are wrong" is rather weak and "I don't know" is not a real distractor. This weakness could have been reduced by introducing two other distractors. Alternatively, an open answer with subsequent coding by two independent raters would have been conceivable. In addition, an interferential statistical analysis of the correct answer and the influence of the level of education would have been interesting for this multiple-choice test. The survey of students used a convenience sample, which limits the interpretation of our findings. In addition, the response rate was only just under one third of the respondents, which could have led to a bias, as possibly only particularly interested or particularly good students could have participated in the study. Furthermore, since this is not a longitudinal study, no conclusions can be drawn about curricular aspects or didactic teaching methods. Nevertheless, our study offers first insights that intuitive concepts also exist in internal medicine and that these do not seem to change significantly proportionally with study progress in medical students, which is in line with the initial hypothesis. In some cases, they even increase. As in the natural sciences, intuitive concepts learned from other life contexts [13] seem to overwrite scientific explanations learned in medical school [14], especially when the distance to these curricular contents is large, time pressure exists, or the scientific concept is no longer constantly needed in everyday life. These findings provide initial starting points to focus on correctly learning essential aspects in internal medicine that may lead to later treatment errors due to intuitive concepts, so that students can build error knowledge [5]. The detection of intuitive concepts could also be suitable for other subjects at medical school in order to subsequently develop didactic approaches, e.g. using mnemonic bridges [40], to support students as future physicians not to succumb to intuitive concepts when they encounter them in clinical routine and under time pressure.